Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.msea.2022.144179

researchmap

researchmap

Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Due to great interest in the development of electric vehicles and other applications, improving the performances of lithium-ion batteries (LIBs) is crucial. Specifically, components of electrolytes for LIBs should be adequately chosen from hundreds of thousands of candidate compounds. In this study, we aimed to evaluate some physical properties expected for combinations of molecules for electrolytes by microscopic simulations. That is, the viscosity, ionic conductivity, degree of dissociation, diffusion coefficient, and conformation of each molecule were analyzed via molecular dynamics (MD) simulations. We aimed to understand how molecular-sized structures and properties collaboratively affect the behavior of electrolytes. The practical models of molecules we used were ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL), γ-valerolactone (GVL), dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6). Many molecular systems of electrolytes were simulated, in which one molar LiPF6 was mixed into a single or combined solvent. It was found that small solvent molecules diffused with relative ease, and they contributed to the higher ionic conductivity of electrolytes. It was clarified that the diffusion coefficient of lithium (Li) ions is greatly affected by the surrounding solvent molecules. We can conclude that high-permittivity solvents can be selectively coordinated around Li ions, and Li salts are sufficiently dissociated, even when there is only a small content of high-permittivity solvent. Thus, we can confirm solely by MD simulation that one of the better candidates for solvent molecules, formamide (F), will exhibit higher performance than the current solvents.

DOI： 10.3390/batteries8030027

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Society of Materials Science, Japan  

DOI： 10.2472/jsms.71.167

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

DOI： 10.1299/transjsme.22-00019

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Trans Tech Publications, Ltd.  

Sulfide was used as solid lubricant, and MoS₂ was popular. It was used industry as powder shape. Sulfur as oil additive; ZDDP, MoTDC were also well known. These composites make tribofilm which prevent seizure, scoring and some tribological troubles. In this paper, sulfides were synthesized by powder metallurgy technics. In addition, these sulfides were mixed with bronze powders and sintered as cylindrical specimen. As a result of the friction test in the lubricated condition, tribofilm were covered with specimen surface. By XPS observation, sulfides and oxides were detected on the specimen surface. In the test, additive was not contained in the lubricant because PAO as base oil was adapted. However, sulfide in the specimen affect the making the tribofilm, especially when bornite (Cu₅FeS₄) was used.

DOI： 10.4028/www.scientific.net/kem.901.164

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.68.317

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Hindawi Limited  

As a sustainable ecosystem, the general firing process for ceramics emits large amounts of CO2 gas; thus in ceramics production, the focus is the nonfiring process; however, the solidification and strengthen mechanism of this nonfiring system, which essentially reacts between surface-activated ceramic particles and a solvent, has not been elucidated to date. The nonfiring process had three steps, i.e., particle surface activate process by grinding process, maintaining the active state until starting nonfiring solidification begins, and nonfiring solidification process. Thus, in this study, the reaction of silica and water was simulated by adapting molecular dynamics based on LAMMPS with ReaxFF potentials. Reproducing the activated silica surface state, three ended models called O model, Si model, and OH model were prepared which indicated ended molecules of each surface. These models and a water molecule as a solvent were bonded in the atomic scale, and the energetic state and mechanical properties were evaluated. A reacted or structured O-H-O bond was reproduced in the nonfiring process in the O-ended model. The bond was a hydrogen bond. A Si-O-Si bond was produced when a Si atom was ended on the interface. The bonded interface was able to tensile. However, the tensile strength was weaker than that of the solid silica model. The nonbonded OH model did not have tensile strength.

DOI： 10.1155/2020/8857101

researchmap

Other Link： http://downloads.hindawi.com/journals/jnm/2020/8857101.xml

researchmap

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

DOI： 10.1299/transjsme.19-00206

researchmap

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Sufides as MoS₂ are known as solid lubricants. These materials are also known as thermoelectric materials. However, there is no materials satisfied both functions at the same time. In this study, sulfides powders such Cu₂S (chalcocite), SnS, Cu₅FeS₄ (bornite) were synthesized under vacuum condition. Some specimens were evaluated by friction tester and their lubricity, not only sintered sulfied but also blended and sintered sulfides with bronze powders were compared. Other specimens were evaluated their seebeck coefficients, that is one of the thermoelectric properties. Experiments results of the seebeck coefficients were compared with simulation results. As a result, it was found that SnS and blended SnS with bronze had indicated better friction properties. For thermoelectric properties, seebeck coefficient of Cu₂S had matched with experiments and simulation. Totally, Cu₂S (chalcocite) has superior properties as both solid lubricant and thermoelectric material.

DOI： 10.1299/jsmeiip.2017.A-14

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Recently, the fuel consumption improvement by weight saving is required in transportation machine. Therefore, Mg alloy is expected as the alternative material of Al alloy and resin material, because it is the lightest in the practical metals and its specific intensity is high. However, twin crystal deformation occurs easily, and there are the two kinds types (i.e. {1012} and {1011} twin crystal) in that deformation. It has been reported that the {1012} twin crystal has work to relax the stress concentration and the {1011} twin crystal has close relation to fracture. Our aim is to evaluate the kinds and the conditions of those types with AE method. In this study, Mg alloy AZ31 was used, and the AE signals of the alloy were detected in compression, tensile and CT test. After that, the analysis of those signals were done. From the results obtained under this experimental conditions, the following things became clear. (1) The frequency components near 250, 550 and 850 kHz are caused by slip, twin crystal deformation and crack growth respectively. (2) It is possible that the two kinds crystal deformation types are discriminated by the identification standards decided by the AE count and fractal dimension Fd of the detected signals.

DOI： 10.1299/transjsme.16-00027

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

SMA (Shape Memory Alloy) is utilized in various fields. Especially, Ti-Ni alloy has excellent features than other SMA. And, the alloy has two kinds of the phase transformations of rhombohedral (R) and martensitic (M) phase. Though R-phase transformation is not suitable for large deformation, it has been reported that its function for the cyclic deformation is steady. However, the detailed regulation for evaluating the function deterioration and life of the transformations has not been determined, because each factor affects the complexity to each other. Therefore, the establishment of the technique which evaluates the deterioration by the cyclic deformation is desired. In this study, the features of the AE (Acoustic Emission) signals detected in tensile and cyclic deformation test and the structure analysis results of the simulation with MD (Molecular Dynamics) method were compared. As the results, the following things became clear. The frequency components of the signals detected by R- and M-phase were about 750 and 350 kHz respectively. The properties of the signals in each phase showed the chaoticity, and they changed with the increase in the stress. The occurrence behaviors and features of the signals changed with the transitions of the hysteresis loop of σ-ε diagram by cyclic deformation. The generation condition of the R-phase seldom changed in the deformation until rearrangement of R-phase. On the other hand, the conditions on R- and M-phase decreased in the cyclic deformation until M transformation, because the residual phases disturbed the occurrence of M-phase. By observing the simulation results, it was possible to show the existence of the phase transformations of "Austenite (A) phase→R-phase→M-phase" and "A-phase→M-phase". And the correlations between those generation behaviors and the characteristics changes of the signals were recognized.

DOI： 10.1299/transjsme.14-00436

researchmap

環境問題への取組みが始まった頃から，「リサイクル性に優れた構造部材の積極的な利用」や「輸送機械（自動車など）の軽量化による燃費の向上（CO2の排出削減）」などが行われるようになってきた．このため，「実用金属中で最軽量（Al合金の約2/3）」「Al合金と同等の強度」「リサイクル性」「耐くぼみ性」「電磁波シールド性」「放熱性」などに優れるMg合金が注目され，表面処理技術や難燃性の向上により，精密・電子機器および輸送機器や宇宙開発機器などの多岐にわたる分野で使用され始めている．しかしながら，構造部材として使用する場合，その破壊特性を十分に把握・評価しておかなければならないが，これに関する研究は十分であるとはいえない．特に，他の軽金属材料よりも耐熱性と耐食性に劣るので，その使用環境は制限されることになる．よって，高温環境下や腐食環境下での特性変化や破壊形態への影響を機器の稼働中に把握・評価することが望まれている． そこで本研究では，加熱・冷却を繰り返す熱履歴と腐食による機械的特性の影響を非破壊検査法の一つであるAE法を用いてリアルタイムに評価することを検討した．具体的には，「健全材」「熱履歴材」「腐食材」の各試験片に対して引張試験を行い，試験中に放出される弾性波を検出した．そして，「構造部品は許容応力度設計に基づいて作製される」や「弾性変形領域で生じた双晶変形は機械的特性の劣化に繋がる」ことから，弾性双晶変形によるAE信号の特徴を抽出し，その特徴から各使用環境下での機械的特性を予測・評価する手法について検討した結果を報告する．

researchmap

Language：Japanese   Publisher：Japan Foundry Engineering Society  

<p>  The fracture behavior of the white layer on the cast steel brake disc in bending fatigue was evaluated using the acoustic emission (AE) method to analyze the fracture mechanical characteristics. The fatigue strength of the disc material including the white layer tended to be lower than that of the unused material. It was found that the AE signal of the unused material occurred continuously while the white layer occurred suddenly. This clarifies that the fracture of the white layer is brittle. These results indicate that heat cracking occurs easily on the white layer.</p>

DOI： 10.11279/jfes.87.52

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Magnesium alloy is the lightest material in all practical metals, and has the excellent mechanical properties. From such reasons, the alloy is noticed as the attractive material in various fields. However, the alloy has the weak points that are inferior for heat and corrosion resistance. Therefore, it will be possible to guarantee the safety security of structure parts, if the information on the fracture strain and life, etc. are evaluated by the signals detected from the alloy under those use environment. The three type specimens of the virgin, the heat history (<i>i.e.</i> repeatedly gave the heating to the virgin specimen) and the corrosion specimen (<i>i.e.</i> immersed the virgin specimen into solution) are prepared in this study. Then, the tensile test was carried out for each specimen, and the AE signals emitted in the testing were detected. Frequency and fractal dimension analysis were carried out in order to extract the features of those signals. From such analysis results, the feature extraction of the signal by the elasticity twin deformation was done, because that deformation participates in the degradation of mechanical properties. As the result, the following things became clear under the experimental condition in this study: The frequency component of the signals caused by that deformation is near 550 kHz. The fractal dimensions <i>Fd</i> of those signal show the value over 1.85. Then, it was examined whether the fracture strain is evaluated by the <i>Ib</i> value (Improved <i>b</i>-value) led from the frequency distribution of the <i>Fd</i>. As the result, the effectiveness of this method proposed under the experimental conditions in this study was confirmed. Therefore, the possibility for the prediction of that strain by the AE signal detected in elastic region was shown.

DOI： 10.1299/transjsme.14-00541

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A6061-T6 alloy has been used in the liner material of high-pressure hydrogen gas storage container that is mounted on a fuel cell vehicle. The degradation of the properties such as strength, toughness and hydrogen embrittlement resistance, etc., has been pointed out, because the grain structure of the mouthpiece part of the liner becomes coarse in the manufacturing process. The tensile and fatigue test for the specimens with different grain size were done, and the detected AE signals during the testing were analyzed. In the tensile test, the characteristics of the signals on dislocation motion, transgranular and intergranular fracture were extracted. In the fatigue test, it was shown that the possibility of which the damage is evaluated by the spectral analysis that utilizes the slope of an approximation straight line in the both logarithmic scale display of FFT analysis result. Then we proposed the amplitude ratio Rv that is the parameter which divided the maximum amplitude of signal for intergranular fracture by that of detected signal, and the correlation between the grain size and the Rv was recognized. These proposed information are able to be utilized in order to evaluate the damage of the container.

DOI： 10.1299/transjsme.2014smm0292

researchmap

The bimetal materials that sintered the powder of lead bronze on the base material (i.e. carbon steel) have the excellent performance as the bearing material. However, the nation or the society is moving on with the planning on the use restriction of lead and lead compound. Therefore, lead-free copper alloy is developed, and the practical applications of the alloy are advanced. However, the mechanical properties of the bimetal material that sintered the alloy powder have not sufficiently been grasped. In this study, the evaluation of the fracture mechanism and that types which arose in the materials was examined. As the results, it was possible to grasp or evaluate each fracture type by the frequency component of Acoustic Emission (AE) signal with Fast Fourier Transform (FFT) method, and the m value which is led from the amplitude distribution of the signal. By using the criterion for recognizing each type, it was proven that the proposed technique in this study can evaluate the fracture mechanism of each bimetal material which changed the type of the lining material.

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORPORATION  

Fiber Bragg grating (FBG) is an optical fiber sensor and is suitable for acoustic emission (AE) measurements of structures such as chemical plants that require water resistance, explosion proofing, and so forth, However, directionality has been a problem in conventional usage which glues the grating range of an FBG to the inspection surface. This study proposes a cylinder-FBG (C-FBG) sensor with the FBG glued to a cylindrical sensor holder. Effectiveness of the sensor was evaluated by characterizing directionality and frequency sensitivity of the sensor and by comparing the detected AE signals in a 3-point bending test of a carbon fiber reinforced plastic (CFRP) laminate against a conventional wide-band piezoelectric AE sensor. The features of the detected signals were similar to the signals detected by the wide-band AE sensor. These results show that it is possible to produce a wide-band cylindrical sensor without the directionality limitations of the conventional usage of FBG.

DOI： 10.1155/2014/274071

Web of Science

researchmap

researchmap

researchmap

researchmap

Language：Japanese   Publisher：Japan Foundry Engineering Society  

<p>  It is known that the white layers formed on cast steel brake disks for railway that have high hardenability during braking tests become lath martensite, which is a fully quenched microstructure. In this study, such white layers were reproduced on cast steel by sliding friction test, and their microstructure was investigated. Severe friction was applied on the specimens using a WC-Co bar with high pressure which raised the temperature of the specimens to above the material's Ac3 point. These white layers were observed on the friction surface of the specimens after the friction test, and the results of investigations of the microstructure by SEM and TEM identified the white layers to be a sub-micron equal axial microstructure with 30 to 100nm grain. The white layers were different from those formed on brake disks, which are known to be lath-martensite with coarse grain.</p>

DOI： 10.11279/jfes.85.21

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

DOI： 10.11522/pscjspe.2013A.0.559.0

researchmap

researchmap

レーザ溶接・接合の特長は，『微小スポットへの集光による高いエネルギー密度と溶接速度の高能率化』『熱影響層が小さく，変形やひずみの少ない高品質で高精度な溶接が可能』である．特に，YAGレーザによる溶接は作業空間に余裕のない狭い場所や遠隔部での精密加工性とフレキシブル性に優れていることから，電子部品や薄板などの加工に用いられている．しかし，『溶融現象の解明や接合部の信頼性と安全性に関する研究は十分ではない』『照射条件のみで所望の溶込み状態が得られるような単純な作業ではなく，溶接の良否は技術者の技能に依存される』ということから，作業中に得られる情報から溶込み状態を把握・評価する手法の確立が望まれている．そこで前報では，レーザによる溶接加工の需要が高く，耐食性などの機械的特性に優れているSUS304ステンレス鋼にYAGレーザを照射したときの『AE信号の特徴』と『溶込み状態』との関係を調べた．具体的には，レーザ照射中に検出される信号のwavelet変換結果と熱伝導解析プログラム（Quick-Therm：㈱計算力学研究センター）による融点到達時間のシミュレーション結果から，溶込みに起因して発生するAEの周波数帯域は300kHz付近（225～375kHz）であることがわかった．そして，検出されたAEの特徴から溶込み状態を評価するために，AEの特徴を説明変数，溶込み状態（溶込み幅：W，溶込み深さ：D，溶込み面積：S，溶込み角：θ）を目的変数とする回帰式を作成し，その有効性を回帰式の予測値と実験値との相関係数|r|で評価した．その結果，横波検出用センサでの検出波のAEエネルギーから溶込み状態を評価する回帰式を作成することができた．しかし，環境雑音が飛び交う溶接現場での信頼性を高めるには，複数の情報を総合して評価することが望ましい．そこで，300kHz付近のAEの不規則性や複雑さをカオス解析で調べたところ，サンプリング（0.5μs）毎のwavelet係数を加算して得られるエネルギー率の時間変動波形にカオス性が認められた．そして，カオス解析結果と溶込み状態の関係を調べた結果，縦波検出用センサで検出したAEの最大リアプノフ指数LLyから溶込み状態を評価する回帰式を導くことができた．このようなことから，照射中に検出されるAEの特徴から溶込み状態をリアルタイムかつ定量的に把握・評価できる可能性を示すことができた．しかし，生産性・省力化・品質保証の更なる向上が要求される生産現場では，前報で示したパルス幅のみではなく，ランプ印加電圧による照射エネルギーの変更にも対応できるかを把握しておかなければならない．なぜならば，同じ照射エネルギーでも印加電圧が大きければ温度上昇率は大きくなり，それが熱衝撃波の発生状態（周波数成分など）に影響を与えると考えられるからである．そこで本報では，このような状況にも前報の手法を適用できるのかを検討する．そして，印加電圧の変更による温度上昇率の差が熱衝撃波の周波数成分に影響を与え，溶込みの周波数成分と重複するようなことが起こるならば，溶込みに起因して発生する周波数帯域の信号を処理する前報の手法を適用できないので，照射終了後の信号を解析する新たな評価法を提案する．

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

Fiber reinforced plastics(FRP) has become one of the important structural materials in the various fields.Therefore,it is important to evaluate the fracture modes and the fatigue damage of FRP laminates.Acoustic emission(AE) monitoring is useful to study its damage and the modes.However,it is difficult to evaluate the damage and the modes during the fatigue testing.Recently,Wavelet Transform(WT) are the center of attention at the analysis of the signals.The resultant mapping of wavelet coefficients in the time-frepuency coordinate plane provides more informative characterization of the signals than the power-density spectra from Fourier Transform(FT).In this report,the AE signals of CFRP and GFRP laminates(i.e.[0°],[0°/90°] and [±45°])subjecting to cyclic bending loads were recorded at each cycle during the fatigue testing,and were analyzed with WT for evaluating its damage and the modes.By observing the resultant mapping at each cycle,it is possible to develop a methodology for evaluating the damage and the modes by using the characteristic features of the mapping.This system consistes of an AE measuring device and a neural network.The network has learned the pattern sets dealing with the interaction between the features of the mapping and the fatigue damage.The character of the mapping wes expressed by fractal dimensions that were led by the box-counting method.The effectiveness of this system is demonstrated by comparing results of the neural network with experimental data obtained from the fatigue tests.

DOI： 10.2493/jjspe.68.1309

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00158965176?from=CiNii

It is widely used in the industry field,because the ceramics coating materials have many excellent features.However,that clear criterions for evaluation on the character of films have not been determined is made to lower the reliability of the materials.It is necessary to quantitatively grasp the damage conditons and growth in order to determine the criterions.In this study,the technique that quantitatively evaluates the damage conditions of the films with AE method and image processing technique,when the thermal shock was repeatedly given to the film by YAG laser,is proposed.Concretely,the detected AE signals by a laser irradiation are devided into heating and cooling process,and the features of AE signals in the individual process are extracted.And,the fetures of damage conditions in the irradiation area are quantitatively extracted by image processing.The detected AE signals in heating process correspond with the image data on the damage before a laser irradiation.Therefore,the neural network for estimating the damage before an irradiation learned the relationship between the signals and the image data.On the other side,the detected AE signals in cooling process correspond with the image data on the damage growth after an irradiation.Therefore,the network for estimating the damage growth after an irradiation learned the relationship between the signal and the image data.From the output of the two networks,it was possible to evaluate the conditions and the growth of the thermal shock damage.The effectiveness of the constructed network became clear by the comparison with the experimental results.

researchmap

Many of the ceramic coating materials can be exposed to harsh working conditions.Therefore,for producing superior coating materials,it is necessary to establish a methodology for evaluatig the mechanical properties of these materials.Until the former report,nine kinds of TiN film 5┣T00300┫m thick,which were deposited on the differrent parent materials under different N2 partial pressure,were scratched and the relationship between the characteristics of the detected acoustic emission(AE) signals and the fracture modes of the film(i.e. cracking,chipping and flaking)was investigated.As the results,the following things became clear:(1)the fracture modes were classified by fractal deminsion m determined AE peak amplitude distributions.(2)the changes of the fracture mode were evaluated by observing the analysis with wavelet transform(WT).In this report,time fluctuation signals of wevelet coefficient,multiple analysis and fuzzy reasoning were used to evaluate the scratch mark conditions.From the experimental results,it was found that the conditions were evaluated by this method.

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In assuring the safety of a structure,it is important to evaluate the state of structural members non-destructively by magneto-mechanical acoustic emission(MAE).MAE is useful in NDT,because it reflects minute changes of stress and microstructure of ferrous materials.We studied MAE signals of a pure iron using displacement and shear sensors,for the detection of the longitudinal and shear components of the signals,which were analyzed by wavelet transform.The mapping of wavelet coefficients in the time-frequency coordinate plane provides informative characterization of the signals.From the analysis,we found that the low(150 to 300kHz)and high frequency (400 to 800 kHz)components are caused by different magnetization effects.The low frequency component has strong desplacement sensor response coincident with the rate of magnetic induction,suggesting magnetization via the discontinuous motion of domain walls.The high frequency component has strong shear sensor response and is observed near magnetic saturation,suggesting rotational magnetization effect.

DOI： 10.1299/kikaia.68.835

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00156862491?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

Recently,coating materials have been noticed,and are widely used in the several fields.However,it is being taken up as a serious problem that the large-scale destruction of the structure will be occurred at the time when the damage of the coating film generates.On the other hand,the new concept on the active damage control,which the structure member parts adapt itself to the environmental conditions,has been exposed to the attention in the material science.In this concept,they have the function such as a living organism,and do the work in proportion to the environment in the circumference.They are called smart material or smart structure.In short,it denotes that they have the sense organ for detecting the damage in itself,the processor organ for deducing a suitable signal for the damage and the actuator organ for restraining the damage.Therefore,it is a possible by applying the concept of the smart materials and structures to actively restrain or restore the damage.In this study,the basic study on the damage restraint of coating film is proposed.In short,by adopting this concept,the efficiency of actively restoring the damage of the film is reported.

DOI： 10.1299/kikaia.67.1345

Scopus

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

Structural ceramics are attracting attention in the development of space ships,aircraft and nuclear fusion reactors because they have excellent heat-resistant characteristics.Therefore,various structural ceramics have been developed as heat-resistant materials.Especially,ceramics coating materials are widely used because the materials have the characteristics of the both the base materials and the coating materials.However,the ceramics are damaged easily by the thermal stress result from the thermal shock.Therefore,it is necessary to understand their thermal shock properties and to investigate their thermal shock characteristics.In this report,it is discussed to evaluate the cyclic fatigue damage(i.e. crack initiation,crack growth and fracture)for TiN ceramic film during the repeated thermal shock tests.Concurrently with the repeated shocks that irradiated the coating surface wigh YAG laser,acoustic emission(AE) monitoring was carried out to detect the onset of the thermal shock damage,and the surface apperance was assessed by optical micoscope observations.Wavelet Transform(WT) was applied for distinguishiing the signals on damage of TiN from a signal on thermal shock in the first 5 msec of the detected signals.After this processing,the features of the AE signals on the damage of TiN film were analyzed.As the results,it was found that the fatigue damage during the theramal shock tests were evaluated by monitoring the 3-D data which represented the relationship between the slope of amplitude distribution of AE signal,AE events and the number of the repeated thermal shock.

DOI： 10.1299/kikaia.67.906

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

Many of the ceramic coating materials can be exposed to harsh working conditions because of their excellent characteristics.Therefore,for producing superior coating materials,it is necessary to establish a methodology fo evaluating the mechanical properties of these materials.In this study,nine kinds of TiN film of 5┣T00300┫m thickness,which were deposited on different parent materials under differrent N2 partial pressures,were scratched and a method for evaluating the properties of the coating materials with acoustic emission(AE) was developed.The results were as follows:(1)A scratch testing apparatus that can detect AE signals emitted from the TiN film during scratch testing was fabricated.(2)The relationship between the characteristics of the detected AE signals and the fracture modes of the film(i.e.,cracking,chipping and flaking) was investigated.(3)It was clarified that fractal dimension mdetermined from AE peak amplitude distributions became greater than three when the fracture mode was cracking,the dimension became between one and three when the mode was chipping,and the dimension became less than one when the mode was flaking.From these experimental results,it was found that the strength and the adhesivity of thin film can be evaluated from fractal dimension m determined by scratch testing.

Web of Science

researchmap

Carbon-fiber reinforced plastic (CFRP) has become an important structural material in various fields.Therefore,it is important to evaluate the fracture modes and the fatigue damage of CFRP laminates.In the previous paper,the acoustic emission(AE) singals of CFRP laminates (i.e.[0┣T00040┫]11 , [0┣T00040┫/90┣T00040┫]11 and [±45┣T00040┫]11 )subjected to cycle bending loads were recorded at each cycle during the fatigue test,and were analyzed by wavelet transform(WT) to evaluate the damage and fracture modes.By observing the resultant mapping of wavelet coefficients in the time-frequency coordinate plane at each cycle,it was proved possible to recognize the damage and the modes of CFRP laminates using nondestructive inspection.The purpose of this paper is to develop a methodology for evaluating fatigue damage and fracture modes using the characteristic features of the mapping.This system consists of an AE measuring device and a neural network.The network has learned the pattern sets dealing with the interaction between the features of the mapping and the fatigue damage.The character of the mapping expressed by wavelet coefficients in the time-frequency coordinate plane is bracketed wording clear scientifically by fractal demensions that were led by the box-counting method in fractal theory.The effectiveness of this system is demonstrated by comparing results of the neural network with experimental data obtained from the fatigue tests.

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

Many of the ceramic coating materials can be exposed to harsh working conditions because of their excellent characteristics.Therefore,for producing superior coating materials,it is necessary to establish a methodology for evaluating the mechanical properties of these materials.In the former report,nine kinds of TiN film 5┣T00300┫m thick,which were deposited on the different parent materials under different N2 partial pressure,were scratched and the relaionship between the characteristics of the detected acoustic emission(AE) signals and the fracture modes of th film(i.e. cracking,chipping and flaking) was investigated.As the results,it was clarified that fractal dimension m determined AE peak amplitude disributions became grater than three when the fracture mode was cracking,the dimension became between one and three when the mode was chipping,and the dimension became less than one when the mode was flaking.However,it is necessary for evaluating the fracture mechanism to recognize the information on the changes of the fracture modes which is included in an AE event.In this report,wavelet transform(WT) was used to attain the subject.From the experimental results,it was found that the changes of the fracture mode are evaluated by observing the time-frequency analysis with WT.

DOI： 10.1299/kikaia.66.2074

Scopus

researchmap

Carbon fiber reinforced plastics (CFRP) has become one of the important structural materials in the various fields. Therefore, it is important to evaluate the fracture modes and the fatigue damage of CFRP laminates. Acoustic emission (AE) monitoring is useful to study the modes and it is required that we should go on with the study of more elaborate information processing method for evaluating its damage and fracture modes with the AE signals. However, it is difficult to evaluate the damage and the modes during the fatigue testing because the detected signals include the environmental noise during the testing. Recently, Wavelet Transform (WT) is the center of attention at the analysis of the signals. The resultant mapping of wavelet coefficients in the time-frequency coordinate plane provides more informative characterization of the signals than the power-density spectra from usual Fourier Transform. In this study, the AE signals of CERP laminates (i.e. [0┣T00040┫]11, [0┣T00040┫/90┣T00040┫]11 and [┣T00010┫45┣T00040┫]11) subjecting to cyclic bending loads were recorded at each cycle during the cyclic bending testing, and were analyzed with WT for evaluating its damage and fracture modes. By observing the resultant mapping of the coefficients at each cycle, the following things became clear; (1)We could discriminate the different signals by the fatigue damage and the fracture modes at a glance because the mapping illustrated the characteristic features of the signals. (2)It was proved with WT that the several fracture modes and the time difference of which the each fracture mode occur exit in a signal. (3)By using the presented method, it was proved to be able to recognize the fatigue damage and the fracture mode of CFRP laminates with nondestructive inspection.

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

Many of the ceramics coating materials are in use under the hard working conditions on the ground that these materials have the excellent characteristics. Therefore, it is expected for producing the superior coating materials to establish a methodology for evaluating the mechanical properties of these materials. In this report, 9 kinds of TiN film 5┣T00300┫m thick that were deposited on the different parent materials under the different N2 partial pressure were scratched and a method for evaluating the properties of the coating materials with Acoustic Emission (AE) is described. Its contents are follows: (1) The scratch testing apparatus that can detect the emitted AE signals from the TiN film during the testing was produced. (2) The relationship between the character of the detected AE signals and the fracture types of film (i.e. crack, chipping and flaking) were investigated. (3) It was became clear that the fractal dimension m led from AE amplitude distribution shows more than 3 when the fracture type is crack, the value shows between 1 and 3 when the type is chipping, the value shows less than 1 when the type is flaking. From these experimental results, it was found that the strength and the tight-adhesiveness of thin film are evaluated by observing the fractal dimensions of AE amplitude distribution during the scratch testing.

DOI： 10.1299/kikaia.65.1696

Scopus

researchmap

Structural ceramics are attracting attention in the development of space ships, aircraft and nuclear fusion reactors because they have excellent heat-resistant characteristics. Therefore, various structural ceramic have been developed as heat-resistant materials. Especially, ceramics coating materials are widely used because the materials have the characteristics of both the base materials and the coating materials. However, the ceramics are damaged easily by the thermal stress result from the thermal shock. Therefore, it is necessary to understand their thermal shock properties and to investigate their thermal shock characteristics. In this report, it is discussed to evaluate the cyclic fatigue damage (i.e. crack initiation, crack growth and fracture) for TiN ceramic film during the repeated thermal shock tests. Concurrently with the repeated shocks that irradiated the coating surface with YAG laser, acoustic emission (AE) monitoring was carried out to detect the onset of the thermal shock damage, and the surface appearance was assessed by optical microscope observations. Wavelet Transform (WT) was applied for distinguishing the signals on damage of TiN from a signal on thermal shock in the first 5 msec of the detected signals. After this processing, the features of the AE signals on the damage of TiN film were analyzed. As the results, it was found that the fatigue damage during the thermal shock tests were evaluated by monitoring 3-D data which represented the relationship between the slope of amplitude distribution of AE signal, AE events and the number of the repeated thermal shock.

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

It is very important to evaluate damage levels of structures for prediction of fatigue fracture. Purpose of this study is to develop a methodology for evaluating fatigue damage and conditions by a nondestructive inspection technique. Low cycle fatigue test were conducted for carbon steel specimens (0.15 and 0.45 wt% carbon) under various fatigue conditions. During the tests, magnetic properties and a magnetomechanical acoustic emission were measured at predetermined number of cycles. The test results exhibited 480 pattern sets which describe the relationship between the measured parameters and the fatigue information such as the damage level (Cycle ratio N/Nf), the stress amplitude (┣T00330┫a) and the stress ratio (R). A nondestructive evaluation system consisting of measuring and a neural network was proposed. The effectiveness of this system was demonstrated by comparing results of the neural network with experimental data obtained from the fatigue tests.

DOI： 10.1299/kikaia.64.2862

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00056884708?from=CiNii

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Recently composite laminated plates made from the prepreg sheet of the woven fabric have been produced and used. When the materials are used, the laminated construction must be optimized to use it effectively. The purpose of this study it to propose the support system for the design of the laminated construction of the woven fabric (i.e. Carbon, Glass and Aramid). The system consists of Genetic Algorithm and Neural Network. By repeating the following two sequences, the designs that satisfied the required mechanical properties are searched. (1)The character of the laminated construction of the woven fabric that was expressed by binary number is produced according to Genetic Algorithm. (2)The fitness grade of the designs to the required properties are evaluated by Neural Network. The network has learned the pattern information which is expressed by the relationship between the codes and the mechanical properties (density and tensile strength). The several composite laminated plates which were recommended by this system were produced, and the properties of the plates were measured. As the results, it was proven that the measurements are close to the required properties, and the validity of the system was confirmed.

DOI： 10.1299/kikaia.64.2080

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00054997400?from=CiNii

Acoustic emission monitoring is useful to study the fracture modes and kinetics in various materials. The discontinuous motion of magnetic domain walls in ferromagnetic materials during magnetization produces Acoustic Emission. The emission is called Magnetomechanical Acoustic Emission (MAE).MAE behavior shows a sensitive dependence on the change of the structure in ferromagnetic materials. Our aim is to estimate the accurate stress imposed on the structure's member parts by monitoring MAE signals. IN this report, it is described whether Wavelet Transform (WT) of MAE signals is powerful new method for estimating the accurate stress. The MAE signals of carbon steel were measured with a displacement sensor at each tensile stress during the elastic region. From the results of WT of the signals, it was became clear that we could discriminate the different signals by applying tensile stress at a glance because the mapping of wavelet coefficients in the time-frequency plane illustrated the characteristic features of the signals. Therefore, we could find out possibility of which the accurate stress imposed on the structure's member parts will be estimated by monitoring the features of the map.

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The nondestructive inspection of the welded region is very important for quality control. The purpose of this study is to develop a methodology for nondestructive evaluation of the function of the spot-welded joint. In the previous paper, the system that consist of an ultrasonic inspection device and neural network was proposed to evaluate the tension-shearing load. The welded region's geometry in resistance spot welding of a two-plate joint was inspected by parallel scanning over the region by ultrasonic inspection. The neural network learned the pattern sets dealing with the interaction between the scanning graphs and the tension-shearing load of spot-welded joints. The validity of the previous system was confirmed by comparing the output of the network with the experimental results. However, it had been serious problems for improving the accuracy of the tension-shearing load that the learning efficiency of the network was not good and the internal structure of the network were involved (the number of the input layer's units was 2401units), In this paper, fractal dimension is introduced to characterize the scanning graphs, and the application of the dimension is proposed as the input data of the neural network. The following became clear after the investigation: (1)The scanning graphs showed fractal characteristics. (2)The number of the input layer's units was reduced from 2401 to 98. (3)The accuracy of the evaluation and the learning efficiency of this network were much better than the previous network.

DOI： 10.1299/kikaia.64.1375

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00053324726?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG  

The resistance welded joint is widely used as a structural part. Therefore, it is desirable to establish the nondestructive inspection method for quantitatively estimation the quality of the joint. In this paper, the system based on a neural network was proposed to estimate the tension-shearing load of spot-welded regions from their ultrasonic scanning graphs. The following became clear after the investigation: (1)this system, trained on many sets of experimental data, was able to produce good results from various scanning graphs, and (2)it was proven that this method of processing the information of the welded site is valid as a means of evaluation the tension shearing load of spot-welded joints.

Web of Science

researchmap

Language：Japanese  

It is very important to evaluate damage levels of structures for prediction of fatigue fracture. The purpose of this study is to develop a methodology for evaluating fatigue damage and conditions by a nondestructive inspection technique. Low cycle fatigue tests were conducted in a 0.45% carbon steel under various fatigue conditions. During the tests, magnetomechanical acoustic emission and magnetic properties were measured at the predetermined number of cycles. The test results exhibited 256 pattern sets which describe the relationship between the measured parameters and the fatigue information such as damage level (Cycle ratio N/Nf), stress amplitude (┣T00330┫a) and stress ratio (R). A nondestructive evaluation system consisting of a measuring apparatus and a neural network is proposed. The effectiveness of this system is demonstrated by comparing neural network results with the experimental data obtained from the fatigue tests.

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The spot-welded joint is widely used as a structural part. Therefore, The nondestructive inspection of the welded region is very important for quality control. In this study, by parallel scanning over the welded region by ultrasonic inspection with a point-focused probe, its geometry in resistance spot welding of a two-plate joint was inspected. As a result of the inspection, the periphery of the spot weld was identified by the sharp minimum pattern in the scanning graphs of a sound spot weld. When the spot weld included a shrinkage cavity or blow hole in the wielded region, different patterns appeared in scanning graphs, so that the tension shearing load determined by testing was also different in the case of these patterns. Therefore, it is probable that the information for evaluating the load is included in the scanning graph obtained by ultrasonic inspection. Our aim is to develop a methodology for nondestructive evaluation of the function of the spot-welded joint. The present study is an attempt to construct an evaluation system for tension shearing load of the joint. The system consists of an ultrasonic inspection device and neural network. The network learned the pattern sets dealing with the interaction between the scanning graphs and the tension-shearing load of spot-welded joints. The output from the system was examined by comparing it with the experimental results and the validity of the system was confirmed.

DOI： 10.1299/kikaia.62.776

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00038844263?from=CiNii

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In recent years, production systems such as CAD have been proposed, which have exceptional information on design. This research is to develop a methodology for materials selection in the design process. In the previous paper, a consultation system was proposed to select the suitable materials. The system consisted of a neural network which has learned the patter dealing with the interaction between the function of products and materials. Knowledge from literature and the designers' experience in materials selection were incorporated into the pattern information. However, the system was stiff in that it led only to the selective order of the 40 kinds of materials which were stationed at the output layer of the neural network. The aim of present study is to construct a system with flexibility. This system consists of a neural network and an information integration method. The former learns the pattern sets dealing with the interaction between the function of products and ingredients of material. The letter draws the order of priority of suitable materials from the ingredients of material which are evaluated by the neural network. The output from the system was examined by comparing it with the knowledge from literature and designer, and the validity of the system was confirmed.

CiNii Books

researchmap

In order to improve machining efficiency, it is necessary at each cutting process to select the optimum tool. Therefore, the importance of tool management which considers the features of each cutting tool has been recognized. In the 1st report, a structural model based on a neural network was proposed to estimate the rest of tool life time, and it is one of the most important information on the management. In this paper, the tool management system is proposed to select the most appropriate from a collection of cutting tools. This system consists of a data base block, estimation block and tool selection block. The data base block is in charge of the information (e.g. tool geometry, rest of tool life, measurement value such as cutting force) on tool selection. The estimation block is composed of the three neural network for estimating the information at the early turning, latter turning or life time under the given machining conditions. The tool selection block decides the order of selection with the information integration method. The following became clear after the investigation: (1)The estimated information by the networks agreed approximately with the experimental results. (2)The appropriate on the order of tool selection with this method was recognized by comparing the measure of information led from this system with the experiments.

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

The skilled machinist can continuously adjust operation in terms of machining efficiency, merchantability and cost. This adjustment is done by means of cutting conditions. In the previous paper, the system was proposed to simulate the machinist's thinking process which set the appropriate cutting conditions based on evaluation of cutting state. The process was constructed by fuzzy integral and hill-climbing. But it had become a serious problem that the try counts on searching of the appropriate cutting conditions using the previous system were nearly four times as many as the skilled machinist's. In this paper, it proposed that the skilled machinist's know-how for improvement of searching efficiency is systematized by neural network. This system which is constructed by introducing the neural network into the previous system is superior to the previous system. By using this system, the cutting conditions which can get the high evaluation is obtained, and the try counts was half as many as the counts using the previous system. The accuracy of the system's output and the improvement of searching efficiency were examined by the experiments under various cutting conditions in turning, and the validity of this system was confirmed.

DOI： 10.2493/jjspe.61.218

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00031197649?from=CiNii

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

The skilled machinists evaluate exactly the cutting state. Therefore, the study on the modeling machinist's thinking process is progressed recently. In this paper, a rational way for the system monitoring the cutting state in turning is discussed. The proposed system consists of the fuzzy integral model which evaluates the individual cutting trouble (e.g. tool life, chatter, chip controllability) and the neural network which applies to the model depending on machining conditions. The fuzzy integral information that compared the evaluation of machinist with fuzzy integral model. The validity of this system was confirmed by the experiments under various cutting conditions in this study.

DOI： 10.2493/jjspe.60.1014

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00027313053?from=CiNii

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Design is the process of translating an idea or a market need into detailed information from which a product can be made. Each of its stages requires decisions about the materials of which the product is to be made. The number of materials available to a designer is vast under these circumstances, and he must select from this vast menu the material best suited to his task. Thus it requires considerable intellectual effort to choose the material suitable for a certain purpose. In recent years greater cooperation with the designer has been proposed. For example, production system such as CAD have exceptional information of design. Our aim is to develop a methodology for materials selection in the design process. The present study is an attempt to build a consultation system for the selection of suitable materials. The system consists of a neural network which has learned the pattern sets dealing with the interaction between the function of products and materials. Knowledge from literature and the skilled machinists' knowledge on materials selection are incorporated into the pattern information. The output from the system was examined by comparing it with the technical knowledge from literature and designer, and the validity of the system was confirmed.

CiNii Books

researchmap

In advanced manufacturing, it is necessary for the improvement of machining efficiency to select an optimum tool at each cutting process by tool management. Then, one of the most important issues is to estimate the rest of cutting tool life under a given cutting condition as accurately as possible. In this paper, a structural model based on neural network is proposed to estimate the life and the wear type of cutting tools from their image data and cutting conditions. The input of the model is (1)the states of crater wear and flank wear to cutting tool (e.g. grade of brightness caused by surface roughness, profile), obtained as image data, and (2)the cutting conditions. This system consists of the model based on neural network and image processing device. The output of the system was examined by the experiments under various cutting conditions in turning and the validity of the system was confirmed.

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

Cutting conditions have an effect on machining efficiency, machining cost and machining time. Thus, a multitude of methods have been proposed to determine the optimum cutting conditions. But each in itself is specific and has limited applicability to the situation for which it was devised. Hence, it may be said that the cutting conditions which are led from those methods are only sub-conditions in the machining scene. On the other hand, the skilled machinist can continuously adjust operations in terms of machining efficiency, merchantability and cost. This adjustment is done by means of cutting conditions. In this paper, the system is proposed to simulate the machinist's thinking process which set the appropriate cutting conditions based on evaluation of cutting state. The thinking process is constructed by fuzzy integral and hill-climbing. The accuracy of the system's output was examined by the experiments under various cutting conditions in turning, and the validity of the system was confirmed.

DOI： 10.2493/jjspe.60.255

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00025087437?from=CiNii

In the manufacturing system such as FMS, one of the most important issues is to estimate the rest of cutting tool life under given cutting conditions as accurately as possible. In this paper, a system based on neural network is proposed to estimate the life and wear type of cutting tools from their image data and cutting conditions. The input of the system is (1)the states of a cutting tool, crater wear and flank wear, obtained as image data, and (2)the cutting conditions. The validity of the system was confirmed by the examinations under various cutting conditions in turning.

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC PRECISION ENG  

A multitude of methods have been proposed to determine the optimum cutting conditions. But each in itself is specific and has limited applicability to the situation for which it was devised. Hence, it may be said that the cutting conditions which are led from those methods are only sub-conditions in the machining scene. On the other hand, the skilled machinist can continuously adjust operations in terms of machining efficiency, merchantability and cost. This adjustment is done by means of cutting conditions. A purpose of this study is to realize the system into which is introduced the skilled machinist's know-how.

Web of Science

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

The skilled machinists evaluate exactly the tool changing time from observational information in cutting process. Such machining know-how gained through long experience may be regarded in a sense as fuzzy object. Recently, the study on the model representation of this know-how are progressed for making use of automatic working. In this paper, a rational way for the constructed model of evaluating the tool changing time is discussed. The proposed model gives the value of sharpness grade by weighing the observational information of fuzzy measure which the machinist's subjective characteristics in grading the tool changing time are identified. From the applications of model using fuzzy integral it was found that the output of the model agreed approximately with the machinist's evaluation, and that the model became a vary useful method for the monitoring by the in-process measurement.

DOI： 10.2493/jjspe.58.993

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00015478344?from=CiNii

This paper is an attempt to construct a system of setting of the cutting conditions. Primary purpose of this study was constructing a knowledge-base system. This system determines the cutting conditions from modeling machinist's thinking process. The procedures are as follows. (1)A machinist's function of the information processing, which estimates machinability, is possible to be systematized by the neural network. Hence, poor machinability can be recognized from the learned neural network. (2)Machinist's subjective knowledge, which correct the cutting conditions to restrain the poor machinability, can be expressed by the fuzzy production rules. Therefore, the correction value of cutting conditions can be inferred from the composition of fuzzy production rules. (3) It was found from the experiments that fitted cutting conditions was obtained by the constructed system.

researchmap

The skilled machinists carry out a very important role in the advanced manufacturing. Recently, the importance of the machining know-how has been recognized for the development in automatic working. Such heuristic rules gained through long experience may be regarded in a sense as fuzzy object. In this paper, a rational way for the acquisition of and model representation of the machinist's heuristic rules in turning operation is discussed. The main results of experiments are summarized as follows: (1)Using fuzzy logic, the machinist's heuristic rules for control to the dimensional error in diameter of cylindrical workplace under machining were transformed into fuzzy control rules. (2)Fuzzy controller could be constructed with 16 heuristic control rules. (3)In case of cutting test with the present fuzzy control system, every machining accuracy obtained was within the tolerance specified.

researchmap

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

Skilled machinists can predict intuitively trouble in workplace for cutting by glancing at the machine part drawing. Such machining know-how gained through long experience may be regarded in a sense as the fuzzy object. In this paper, a rational way for the acquisition of and model representation of this know-how is discussed. The following became clear after the investigation: (1)Through an analysis of the fuzzy partial order relation among machine part drawing, the attributes of the machine part which show a tendency to develop cutting trouble were clarified. (2)By identifying machinist subjectivity with the fuzzy measure, the know-how of the trouble prediction could be represented by a structural model using the fuzzy integral.

DOI： 10.2493/jjspe.55.1211

CiNii Books

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00226090663?from=CiNii

The skilled machinists evaluated precisely the sharpness of cutting edges by weighing the perceived grinding sound on their scales acquired through the experiences. The purpose of the present paper is to make a suggestion regarding the sharpness evaluation by the model using the fuzzy integral. The constructed model gives the values of sharpness grade by weighing the loudness of the various bands of frequencies on the fuzzy measure which the machinist's subjective characteristics in grading the redress life are identified. From verifying results of the model, it was found that the outputs of the model agreed approximately with the machinist's evaluations and the model became a vary useful method for in-process measurement.

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The present study is an attempt to build a consulting system for decision-making about turning conditions. Our primary was with building a system which attached a great importance to the subjective knowledge of the human experts rather than placing emphasis on objectiveness based on numerical information. The procedures used area as follows. (1)Because the memories of the experts deeply versed in the question of macinability are perfectly possible to be systematized by the threshold logic, the reasonable turning conditions can be derived from the logic. (2)The experience rules of the experts for dissolving the poor merchantability can be expressed by the fuzzy relation. Therefore, the cause can be inferred by using an inverse operation of the composition of the fussy relation, and same pertinent suggestions can be made.

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese  

CiNii Books

researchmap

researchmap

researchmap

researchmap

It is making use of the knowledge of the skilled person for machine processing. But, it is very difficult to make their skill a figure. Skill is because it is formed by a qualitative expression. Fuzzy theory is suitable for solving such a problem. So, building of the production processing software which fuzzy theory was used for was tried by this research. By the collation with the experimental result, it was possible to clarify that the morph is possible in the fuzzy theory in respect of the knowledge on the skill.

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：東京  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：Okinawa, Japan  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：大阪  

researchmap

Venue：東京  

researchmap

Venue：東京  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：東京  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：クリエイションコア東大阪  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Venue：Tokyo  

researchmap

Venue：Tokyo  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

In the previous report, the AE method was applied to the evaluation of bending fatigue damage of the FRP laminates, and the effectiveness was reported. By the way, it becomes important to detect the crack and predict its propagation behavior for securing the reliability and the safety of the structures. Therefore, the studies on the detection of the crack with infrared thermography are carried out. However, in order to predict the behavior of the crack propagation in which the complicated factors are included, it is required that the establishment of the methodology which is able to make good use of the obtained rules from the observational results. In this study, the graph information as the features of the detected crack from the thermal image is collected, and the system which predicts the behavior of the crack propagation on the basis of the found rules from the information is proposed. In short, the graph information in three dimensional space is obtained by processing the thermal images with the order of "subtraction processing ┣T00080┫ extraction of maximum temperature by line measurement ┣T00080┫ application of graph theory". And, the behavior of the crack propagation is predicted on the basis of the degree which is similar to which propagation types in the database. As the results of examining the validity of this system, the following things became clear. (1) It was possible to clarify the thermal distribution and the shape of the crack part by subtraction processing and line measurement, (2) The rules on the graphing of the crack shape were founf from the experimental results and it was possible to quantitatively extract the graph information on the types of the crack propagation, (3) By comparing the experimental results with the predicted results, it was proven that the predictions of this system were appropriate.

researchmap

It is difficult to evaluate the damage of CFRP during the fatigue testing.Wavelet transform(WT) is the useful method at the analysis of the signals.The resultant mapping of wavelet coefficients in the time-frequency coordinate plane provides the informative characterization of the signals.In this report,the AE signals of CFRP laminates subjecting to cyclic bending loads were recorded at each cycle during the testing,and were analyzed with WT for evaluating its damage and fracture modes.By observing the resultant mapping of the coefficients at each cycle,the following things became clear;(1)We could discriminate the different signals by the fatigue damage and the fracture modes at a glance because the mapping illustrated the characteristic features of the singals.(2)It was proved with WT that the several fracture modes and the time difference of which the each fracture mode occurs exist in a signal.(3)By using the presented method,it was proved to be able to recognize the fatigue damage and the fracture modes of CFRP laminates with nondestructive inspection.

researchmap

The AE method for evaluating the soudness of the structural member parts is introduced.And the examples of the application for those techniques that are fractal theory,nerural network and wavelet transform,etc.,are discussed,when detected signal is processed.

researchmap

Many of the ceramic coating materials can be exposed to harsh working conditions. Therefore, for producing superior coating materials, it is necessary to establish a methodology for evaluating the mechanical properties of these materials. Until the former report, nine kinds of TiN film 5┣T00300┫m thick, which were deposited on the different parent materials under defferent N2 partial pressure, were scratched and the relationship between the characteristics of the detected acoustic emission (AE) signals and the fracture modes of the film (i.e. cracking, chipping and flaking) was investigated. As the results, the following things became clear: (1) the fracture modes were classified by fractal dimension m detemined AE peak amplitude distributions. (2) the changes of the fracture mode were evaluated by observing the analysis with wavelet transform (WT). In this report, time fluctuation signals of wavelet coefficient, multiple analysis and fuzzy reasoning were used to evaluate the scratch mark conditions. From the experimental results, it was found that the conditions were evaluated by this method.

researchmap

Fiber reinforced plastics (FRP) has become one of the important structural materials in the various fields. Therefore, it is important to evaluate the fracture modes and the fatigue damage of FRP laminates. Acoustic emission (AE) monitoring is useful to study the modes and it is required that we should go on with the study of more elaborate information processing method for evaluating its damage and fracture modes with the AE signals. However, it is difficult to evaluate the damage and the modes during the fatigue testing because the detected signals include the environmental noise during the testing. Recently, Wavelet Transform (WT) are the center of attention at the analysis of the signals. The resultant mapping of wavelet coefficients in the time-frequency coordinate plane provides more informative characterization of the signals than the power-density spectra from usual Fourier Transform. In this report, the AE signals of CFRP and GFRP laminates (i.e.[0°],[0°/90°] and [±45°]) subjecting to cyclic bending loads were recorded at each cycle during the cyclic bending testing, and were analyzed with WT for evaluating its damage and fracture modes. By observing the resultant mapping of the wavelet coefficients in the time-frequency coordinate plane at each cycle, the following things become clear; (1) We could discriminate the different signals by the fatigue damage and the fracture modes at a glance because the mapping illustrated the characteristic features of the signals. (2) It was proved with WT that the several fracture modes and the time difference of which the each fracture mode occur exist in a signal. (3)By using the presented method, it was probved to be able to recognize the fatigue damage and the fracture mode of the laminates with nondestructive inspection. From the above-mentioned result, it is possible to develop a methodology for evaluating the damage and the modes using the characteristic features of the mapping.

researchmap

The detected AE signals during the bending fatigue test of CFRP and GFRP laminated plates were analyzed with wavelet transform(i.e.WT),and the fractal dimension was used for the quantitative features expresiion of WT results.Then,neural network which evaluate the fatigue damage from the quantitative features of the results and layered structure was constructed,and the effectiveness was clarified by the collation with the experimental result.

researchmap

Many of the ceramic coating materials can be exposed to harsh working conditions.Therefore,for producing superior coating materials,it is necessary to establish a methodology for evaluating the mechanical properties of these materials.Until the former report,nine kinds of TiN film 5μm thick,which were deposited on the different parent materials under different N2 partial pressure,were scratched and the relationship between the characteristics of the detected acoustic emission(AE) signals and the fracrure modes of the film(i.e.cracking,chipping and flaking) was investigated.As the results,the following things became clear:(1)the fracture modes were classified by fractal dimension m determined AE peak amplitude distributions.(2)the changes of the fracture mode were evaluated by observing the analysis with wavelet transform(WT).In this report,time fluctuation signals of wavelet coefficient,multiple analysis and fuzzy reasoning were used to evaluate the scratch mark conditions.From the experimental results,it was found that the conditions were evaluated by this method.

researchmap

Functionally gradient material(FGM),which the mechanical properties change from the surface to the inside,is exposed to harsh working conditions because of its excellent characteristics.Therefore,in order to produce the superior FGM,it is necessary to establish a methodology for recognizing the internal conformation.In this study,fiber-reinforced plastic(FRP) laminated materials were used as a substitute for FGM.The specimens,which the fiber reinforced sheets of carbon and glass were layered ,were scratched.And a method for recognizing the internal conformation with acoustic emission(AE) was proposed.The result were as follows:(1)the relationships between the characteristics of the detected AE signals and the kinds of specimen were investigated;(2)it was clarified that the fractal demension m determined from AE peak amplitude distribusions change depend on the kinds of fiber in the material.From these experimental results,it was found that the conformational recognition of the material could be evaluated from the fractal demension m determined by scratch testing.

researchmap

The new concept on the active damage control,which the structure member parts adapt itself to the environmental conditions,has been exposed to the attention in the material science.The concept is called smart material or smart structure.By introducing the concept,it is possible that the material and the structure have the functions(i.e.,sense,thinking and action)such as a living organism.On the other hand,it is very important to evaluate the fracture and he damage of the coating material,because the enormous damage to society activity is caused by the destruction of the material.In this study,the basic study on the damage restraint of coating film is proposed.The material has a sensor,a processor and actuators,where the sensor detects the damage,the processor deduces a suitable signal in proportion to the damage and the actuator takes an action on the basis of the deduced signal.The effect on the damage restraint of the film is considered from the experimental results.

researchmap

CFRP occupies the important position as a structural material.However,the research on elucidation of the fracture mechanism by the fatigue and evaluation of the damage is being mentioned as an important problem.In this study,AE signals which arose under bending fatigue test of CFRP laminate plates of which the structural property was differs([0°],[0°/90°],[±45°]) were detected.The model which evaluated the fatigue damage and fracture mechanism was constructed with wavelet transform that can grasp the time information of frequency component,and the effectiveness of the model was clarified by the collation with the experimental result.

researchmap

In assuring the safety of a structure, it is important to evaluate the state of structural members non-destructively by magneto-acoustic emission (MAE). MAE is useful in NDT, because it reflects minute changes of stress and microstructure of ferrous materials. We studied MAE signals of a pure iron using displacement and shear sensors, for the detection of the longitudinal and shear components of the signals, which were analyzed by wavelet transform. The mapping of wavelet coefficients in the time-frequency coordinate plane provides informative characterization of the signals. From the analysis, we found that the low (150 to 300 kHz) and high frequency (400 to 800 kHz) components are caused by different magnetization effects. The low frequency component has strong displacement sensor response coincident with the rate of magnetic induction, suggesting magnetization via the discontinuous motion of domain walls. The high frequency component has strong shear sensor response and is observed near magnetic saturation, suggesting rotationalmagnetization effect.

researchmap

The spot-welded joint is widely used as a structural part in any manufacturing fields. In quality control of such joints, one of the most important aspects is to be able to accurately estimate the connective strength using information obtained by non-destructive testing. In this report, a system based on an ultrasonic inspection device and a neural network is proposed for evaluation of the tension-shearing load of each spot-welded joint. The input of the network is the fractal dimension of the scanning data and the output of the network is the load of the joint. The effectiveness of the system was confirmed by comparing the output with experimental results.

researchmap

The discontinuous motion of magnetic domain walls in ferromagnetic materials during magnetization produces acoustic emission (MAE). MAE behavior is influenced by the slightest change in the structure of materials. In this report, we describe a potential method for stress measurement using wavelet transform (WT) of the MAE signal. The MAE signals of carbon steel were measured with a displacement sensor at each tensile stress within the elastic region. It was clear from the results that the wavelet coefficients in the time-frequency coordinate plane illustrate the characteristic features of the signals. Therefore, we could show that the stress of a structure's member parts can be evaluated by monitoring the coefficients

researchmap

The mechanism and the progress of the damage of the structural member part are different by the kind of material, environment and operating history. But the countermeasure has mainly been taken further than the design state in the stage of operation and maintenance. Therefore, the non-destructive inspection that grasps and evaluates degradation condition of member subject will be the important role for the security of safety and reliability of the structure. From such fact, AE (Acoustic Emission) method which processes the elastic wave in deformation and destruction is noticed. AE method has the following feature: it is possible to detect the defect in the narrow place which cannot put the measurement machine and position, and to grasp the crack propagation. Therefore, the development of the method is advanced. The themes in our laboratory (i.e. fractal analysis of the AE signal, wavelet transform of the AE signal and role of AE in smart structure and material) are introduced.

researchmap

The frequent occurrence of impossible expecting trouble becomes a problem, because fatigue breakdown of the FRP which is generated in each place of reinforced fiber and fiber/resin interface and resin is very complicated. In this study, wavelet transform of the detected AE signals during fatigue test of the FRP laminated plate is done. And the result reports fracture mechanism and result of examining whether it is effective for evaluating the damage.

researchmap

There is the magnetism AE (MAE) method in one of the techniques which detect the microscopic structural change of ferromagnetic material. In this study, MAE detected by displacement sensor and Shear sensor was analyzed in FFT and wavelet transform (WT). Based on the analytical result, the behavior of MAE is examined, and the possibility of the non-destructive inspection by MAE is reported.

researchmap

Acoustic emission monitoring is useful to study the fracture modes and kinetics in various materials. The discontinuous motion of magnetic domain walls in ferromagnetic materials during magnetization produces the emission that is called Magnetomecanical Acoustic Emission (MAE). MAE behavior shows a sensitive dependence on the change of the structure in ferromagnetic materials. Our aim is to estimate the accurate stress imposed on the structure's member parts with MAW sensor are powerful new method for estimating the accurate stress during the elastic region. From the results of WT of the signals, it was became clear that we could discriminate the different signals by applying tensile stress because the mapping of wavelet coefficients in the time-frequency plane illustrated the characteristic features of the signals. Therefore, we could find out a possibility of which the accurate stress will be estimated by monitoring the features of the map.

researchmap

It is important for evaluating the safety of the structure to detect the change of the microstructure in the member parts with nondestructive testing (NDT). Magnetomechanical Acoustic Emission (MAE) is one of the useful methods for NDT and its behavior shows a sensitive dependence on the change of the structure in ferromagnetic materials. However, the mechanism on the occurrence and character of MAE do not have been become clear and the method of NDT with MAE is not established. Recently, Displacement sensor and Wavelet Transform (WT) are the center of attention at the measurement and the analysis of AE signals. The sensor detects only the elastic energy by magnetostriction that is origin of the 90┣T00040┫ domain wall motion and rotation of local magnetization in the materials during magnetization. In this report, the detected MAE signals with sensor were analyzed by FET and WT. As the results, it was became clear that the frequency range of the 90┣T00040┫ domain wall motion and rotation of local magnetization are different and we could find out a possibility of which the mechanism of the occurrence of MAE will be clear.

researchmap

Carbon fiber reinforced plastics (CFRP) has become one of the important structural materials in various fields. Therefore, it is important to evaluate the fracture modes and fatigue damage of CFRP. Acoustic emission monitoring is useful to study the modes in various materials. However, it is required that we should go on with the study of more elaborate information processing method for measuring its damage and fracture with AE signals. Recently, Wavelet Transform (WT) is the center of attention at the analysis of the signals. The resultant mapping of wavelet coefficients in the time-frequency coordinate plane provides more informative characterization of the signals than the power- density spectra from usual Fourier Transform. In this study, the signals of CFRP were recorded at each fatigue cycle, and were analyzed with WT. By observing the resultant mapping of the coefficients at each cycle, it was became clear that we could discriminate the different signals by fatigue damage and fracture modes at a glance because the mapping illustrated the characteristic features of the signals.

researchmap

Ceramics films are damaged easily by the thermal shock. In this report, it is discussed to evaluate the cyclic fatigue damage for TiN ceramics film during the repeated thermal shock tests. Concurrently with the repeated shocks that irradiated the coating surface with YAG laser, acoustic emission (AE) monitoring was carried out to detect the onset of the thermal shock damage, and the surface appearance was assessed by optical microscope observations Wavelet Transform (WT) was applied for distinguishing the signals on damage of TiN from a signal on thermal shock in the first 5 msec of the detected signals. After the processing, the features of the signals on the damage were analyzed. As the results, it was found that the fatigue damage during the tests were evaluated by monitoring the 3-D data which represented the relationship between the slope of amplitude distribution of AE signal. AE events and the number of the repeated thermal shock.

researchmap

Many of the ceramics coating material are in use under the hard working g conditions because the materials have the excellent characteristics. Therefore, it is expected for producing the superior coating materials to establish a methodology for evaluating the mechanical properties of the materials. In this report, TiN film 5┣T00300┫m thick were scratched and the relationship between the results of Wavelet Transform of the detected AE signals and the fracture types of film (i. e crack,. chipping and flanking) were investigated. As the results, it was became clear that we could discriminate the different signals of each fracture type at a glance because the mapping of wavelet coefficients in the time-frequency plane illustrated the characteristic features of the detected AE signals. Therefore, we could find out a possibility of which the accurate fracture type will be evaluated by monitoring the features of the map during the scratch testing.

researchmap

Acoustic emission monitoring is useful to study the fracture modes and kinetics in various materials. The discontinuous motion of magnetic domain walls in ferromagnetic materials during magnetization produces Acoustic Emission. The emission is called Magnetomechanical Acoustic Emission (MAE). MAE behavior shows a sensitive dependence on the change of the structure in ferromagnetic materials. Our aim is to estimate the accurate stress imposed on the structure's member parts by monitoring MAE signals. In this report, it is described whether Wavelet Transform (WT) of MAE signals is powerful new method for estimating the accurate stress. The MAE signals of carbon steel were measured with a displacement sensor at each tensile stress during the elastic region. From the results of WT of the signals, it was became clear that we could discriminate the different signals by applying tensile stress at a glance because the mapping of wavelet coefficients in the time-frequency plane illustrated the characteristic features of the signals. Therefore, we could fine out a Possibility of which the accurate stress imposed on the structure's member parts will be estimated by monitoring the features of the map.

researchmap

It is very important to detect the remaining life and the stress history of the structure's member parts with non-destructive inspection, when we evaluate the fatigue damage of the parts. In this paper, the low-cycle fatigue testing of carbon steel S45C was done. And the relationships between the behavior of MAE and the magnetic characteristic by the microscopic structural change of the material were examined. By observing the relationships, the method for evaluating the degree of fatigue damage (N/Nf) and the fatigue conditions (stress amplitude ┣T00330┫a and stress ratio R) was proposed. The following things became clear after the results of exam. (1)Each parameter (i.e. AE counting, average phenomenon energy, maximum amplitude voltage) of MAE reaches the peak by rapidly increasing in the initial stage of the fatigue damage. And the parameter decreases to minimum degree at the fatigue damage 0.25. (2)The behavior on each parameter of MAE signals is different by the fatigue condition of stress amplitude and stress ratio. (3)The saturation magnetic flux density shows the tendency which decreases with the increase in fatigue damage. (4)Though in case of the completely reversed tension and compression, the behavior of saturation magnetic flux density with degree of fatigue damage is different by the stress amplitude, and it is not different in the pulsating tension. (5)The neural network that learned the characteristic of magnetic and MAE signal could estimate the degree of fatigue damage and fatigue condition.

researchmap

It is reported that the fracture characteristics of TiN film that coated on the SUS substrate are evaluated by using the AE event count and the fractal dimension m theory led from the amplitude detected in scratch testing (normal load is continuously taken).

researchmap

The welded material is used for the component of various products. Therefore, it is desired to evaluate the function (for example, shearing strength and tensile strength, etc.) and control the quality of the material with non-destructive inspection. In this study, AE wave (MAE: Magnetomechanical Acoustic Emission) detected in the process which magnetizes weld zone of the spot welding joint was measured, and the relationship between the welded area and the tensile-shear load was examined. Then, the result of examining whether it could apply MAE as a non-destructive examination of spot welding member is reported.

researchmap

It is desired to quantitatively evaluate the heat-resistance of the coating materials with hard anoxic oxidation film. Then, thermal shock fatigue test by a YAG laser was carried out for TiN film made on SUS304 substrate by ion plating in this study. As a result of examining the relationship between AE and the film's image data, the following things became clear. (1) Between AE detected under test and image information (i.e. area proportion and lattice point number) which characterizes damage state of a film, there was the fixed relation regardless of the difference between laser irradiation conditions (i.e. the irradiation energy) in this experiment. (2) By formulating the relationship between detected AE and image information of part of damage, the possibility of quantitatively evaluating the damage state of a film from AE detected under test was able to be shown.

researchmap

The material which raised the heat-resistance by coating on the surface of the metallic material with hard anoxic oxidation coatings, has been used under the severe use environment in the high temperature. From such fact, it is desired that the evaluation method for quantitatively grasping thermal shock resistance of a film formed on the surface is established. In this study, thermal shock fatigue test by a YAG laser was carried out at TiN film made on SUS304 substrate by ion plating in this study. As a result of examining the relationship between AE detected at this time and image information which characterizes damage state of a film, it was proven that the damage state of a film could be quantitatively evaluated from the AE signal.

researchmap

It is very important to detect the degree of fatigue damage and the fatigue condition of the member subject with no-destructive inspection, when forecast and design technique of the fatigue breakdown for the structure are improved. In this study, low-cycle fatigue testing (i.e. pulsating tension and completely reversed tension and compression) of carbon steel S45C for mechanical structure was carried out, and information on magnetic characteristic and magnetism AE was collected. The system applying the neural network that evaluate the degree of fatigue damage (cycle ratio) and fatigue condition (stress amplitude and stress ratio) was constructed and the validity of the output of the system was reported.

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap